https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96247
Bug ID: 96247
Summary: -falign-functions=0 works wrongly
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: hujiangping at cn dot fujitsu.com
Target Milestone: ---
When reading the description of -falign-functions=n in doc/invoke.texi
or gcc man page, I did the following test and found a problem.
---
> # sed -n '11333,11334p' invoke.texi
> If @var{n} is not specified or is zero, use a machine-dependent default.
> The maximum allowed @var{n} option value is 65536.
>
> $ cat hello.c
> int foo() {
> int s = 0;
>
> for (int i=0; i < 10; i++) {
> s += i;
> }
>
> return s;
> }
>
> $ /home/extra_mnt/cross_build_gcc/bin/aarch64-linux-gcc -falign-functions -S
> hello.c; mv hello.s hello.s.align
> $ /home/extra_mnt/cross_build_gcc/bin/aarch64-linux-gcc -falign-functions=0
> -S hello.c; mv hello.s hello.s.0
> $ diff -u hello.s.align hello.s.0
> --- hello.s.align 2020-07-20 10:57:30.660038984 +0800
> +++ hello.s.0 2020-07-20 10:57:33.689038984 +0800
> @@ -2,7 +2,6 @@
> .file "hello.c"
> .text
> .align 2
> - .p2align 4,,11
> .global foo
> .type foo, %function
> foo:
>
>
> $ /home/extra_mnt/cross_build_gcc/bin/aarch64-linux-gcc --version
> aarch64-linux-gcc (GCC) 11.0.0 20200519 (experimental)
> Copyright (C) 2020 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions. There is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
---
I think the compiler's behavior is inconsistent with the doc, the
assembly code should be no defference when -falign-functions option
or -falign-functions=0 option is specified.
I found that the parameter which the target sources like
gcc/config/aarch64/aarch64.c used was the command line argument
'0', not the machine-dependent parameters which should overide the
'0'. So I have submit a patch to gcc-patches list, but still have no
comments.
